Resins with phosphorane pendant groups and process for preparing same

ABSTRACT

Novel carbon-to-carbon cross-linked resins having a plurality of phosphorane pendant groups are prepared by dehydrohalogenating the corresponding haloalkyl phosphonium salt. The phosphoranecontaining resins are useful for converting ketones or aldehydes to olefins via the Wittig reaction. The pendant groups of the novel polymers have the structure   WHERE R1 and R2 each independently is an alkyl or aryl group and R3 and R4 each independently can be hydrogen, alkyl, aryl, acyl, carbalkoxyl, carbamido or cyano group.

United States Patent 91 McKinley et al.

[54] RESINS WITH PHOSPHORANE PENDANT GROUPS AND PROCESS FOR PREPARINGSAME [75] Inventors: Suzanne V. McKinley, Wellesley; Joseph W. Rakshys,Jr., Framingham, both of Mass.

[73] Assignee: The Dow Chemical Company,

Midland, Mich.

[22] Filed: Apr. 8, 1971 [21] Appl. No.: 132,606

[52] U.S. Cl ..260/80.71, 260/8078, 260/87.5 C, 7 260/881 P, 204/1592[51] Int. Cl. ..C08f 19/00, C08f 15/40 [58] Field of Search ..252/426;260/8071, 87.5 R, 260/875 C, 80.78, 88.1, 88.1 P

[56] References Cited UNITED STATES PATENTS 2,398,736 4/1946 Dreisbach..260/87.5 R 3,294,764 12/1966 Pellon 3,300,461 l/1967 Olive 3,444,2085/1969 McClure ..260/590 51 Apr. 3, 1973 Primary Examiner-James A.Seidleck Assistant Examiner-Roger S. Benjamin AttorneyGriswold &Burdick, Stephen l-loynak and Glwynn R. Baker [57] ABSTRACT R1-P=CR3R4where R, and R each independently is an alkyl or aryl group and R and R,each independently can be hydrogen, alkyl, aryl, acyl, carbalkoxyl,carbamido or cyano group.

17 Claims, No Drawings RESINS WITH PHOSPHORANE PENDANT GROUPS ANDPROCESS FOR PREPARING SAME BACKGROUND OF THE INVENTION Methods forpreparing monomeric alkylidene phosphoranes and their use in thepreparation of olefins by reactions with ketones or aldehydes aredescribed in Organic Reactions Volume 14, 1965. In general, these Wittigreagents are prepared by the action of a base on a triphenylalkylphosphonium halide, 1

under anhydrous and oxygen-free conditions. Examples of bases used arephenyllithium, butyllithium, or potassium t-butoxide.

The Wittig reaction heretofore has been carried out in solution, andoften by generation of the alkylidene phosphorane reagent in situ. Insuch a process the excess reactants must be separated from each otherand also from the phosphine oxides which form during the conversion ofthe carbonyl compound to the olefin. The phosphine oxides are generallyless soluble, but not completely insoluble, in the reaction medium.Thus, obtaining products free of organophosphorus contaminants is quitedifficult.

The use of cross-linked resins having alkylidene phosphorane pendantgroups for effecting the Wittig reaction avoids the problems ofseparating organophosphorus compounds from the reaction medium and alsofrom contamination with excess of alkylidene phosphorane.

An object of this invention is the provision of a novel polymericproduct having a carbon-to-carbon backbone cross-linked withcarbon-to-carbon bonds, and having a plurality of alkylidene phosphoranependant groups.

Another object is the provision of novel cross-linked, insoluble, butorganic solvent swellable, polymers having a plurality of alkylidenediaryl phosphorane pendant groups.

Another object is the provision of a method for preparing the saidcross-linked resins having alkylidene phosphorane groups.

SUMMARY OF THE INVENTTON This invention relates to addition polymers,crosslinked through carbon-to-carbon linkages, having a plurality of (lo ylllvr chain) pendant groups on the polymer backbone or main chain. Inthe above formula the pendant groups are also attached to thecross-linked backbone through saturated carbon-to-carbon bonds. Thephosphorus atom can be attached to the phenylene group in the ortho,meta or para position. R and R can be any alkyl group, either straightor branched chain, a C C cycloalkyl group which can have aryl oraliphatic substituents, or an aryl group which can have from one to fouraliphatic hydrocarbon substituents. When R, or R is an alkyl group it ispreferably one having one to 10 and more preferably one to four C atoms.When R or R is a cycloalkyl group it is preferably one having 5 to 8 Catoms. It can be substituted or unsubstituted. If substituted with alkylgroups, the cycloalkyl group can have from one to the sum of the carbonatoms in the ring minus one. The alkyl substituents preferably have fromone to about four C atoms per substituent. When R and R are alkyl R, andR., can be independently an aryl group or a substituted derivativethereof, as defined under R and R above, a hydrogen atom, an alkyl groupof from one to about 10 C atoms or a cycloalkyl group or a substitutedderivative thereof, as heretofore defined. When R and R each isindependently a hydrogen atom, an alkyl group or a cycloalkyl group, thepreferred combination of R and R is that which will result in the C atomof the methylene group bearing R and R being less substituted than the Catom of R, and R to which phosphorus is bonded. R and R combined canalso represent the fluorene moiety defined above or a group attached tothe phosphorus atom and when R and R are both alkyl groups and R is H,alkyl or cycloalkyl R can be an acyl group of one to 10 atoms,preferably one to six atoms, a carbalkoxyl group of from one to 10 Catoms, a carbamido group or a cyano group.

When R or R is an aryl group, which is the preferred group for R R itcan be a mono or a polycyclic substituted or unsubstituted group. Thepolycyclic groups, preferably bi or tricyclic, include naphthyl,biphenylyl, anthranyl, phenanthryl, or the like. When substituted, it ispreferable that the substituent be an alkyl group of from one to four Catoms. The number of substituents on each ring can range from one tothat sufficient to substitute each hydrogen atom on the aromatic ringwith an alkyl group. When R, and R are both aryl groups, the mostpreferred structures, R and R, can include any of the groups definedbelow. The preferred aryl groups are phenyl, tolyl, and xylyl.

R and R each is independently, a hydrogen atom, an alkyl group of fromone to about 10 C atoms or a substituted derivative thereof. R and Rcombined can represent the portion of a fluorenyl moiety, and when R isH, alkyl or cycloalkyl R can be an aryl group either mono or polycyclicor a substituted derivative thereof, or as defined under R, and R above,an acyl group of one to 10 C atoms, preferably one to six C atoms, acarbalkoxyl group of from one to 10 C atoms or a cyano group.

The crosslinked polymers having a plurality of alkylidene phosphoranependant groups can be prepared by dehydrohalogenating the correspondingalkylphosphonium halides. The dehydrohalogenating agent is preferablyone which does not form water on reacting and necessarily is with highlyreactive ylids of this invention. It can be an alkali metal hydrocarbylcompound, including aromatic or aliphatic hydrocarbon alkali metalcompounds or any base which will abstract hydrohalide from thephosphonium salt. The preferred dehydrohalogenation agents arehydrocarbon lithium or sodium compound, including phenyllithium, tbutyllithium and sodium dimethyl sulfoxide anion (NaClIzS CH1) Incarrying out the reaction the cross-linked polymer with alkylphosphonium halide groups is first swollen in a solvent which does notreact with the dehydrohalogenating agent or the alkylidene phosphoranegroup. The solvents which are useful for this purpose includetetrahydrofuran and other cyclic ethers having four to eight C atoms,dialkyl sulfoxides having from one to four C atoms in each alkyl group,sulfolane (tetramethylene sulfoxide), hexamethylphosphoramide,dimethoxyethane other dialkoxy alkanes having from four to C atoms, ormixtures thereof. The dialkyl sulfoxides can be symmetrical orunsymmetrical. Dimethyl formamide is also useful in those instances whenan alkali metal hydroxide is used as the hydrohalide extracting agent.

Because of the reactivity of the alkylidene phosphorane group, thereaction is preferably but not necessarily carried out in an oxygen-freeatmosphere and under anhydrous conditions. Such conditions are necessarywhen the alkylidene group (=CR R contains substituents such as ahydrogen atom, aryl group, or cycloalkyl group. Such conditions aredesirable but not required when the alkylidene portion containingelectron-withdrawing substituents, such as acyl, carbalkoxyl or cyanogroups. An oxygen-free atmosphere can be provided by sweeping with anyof the noble gases (neon, helium, xenon, argon or krypton) or nitrogen.The solvents can be dried before use with calcium hydride, anhydroussodium sulfate, sodium metal or by any other known means.

There are several methods for making the alkyl phosphonium halideprecursors. One procedure comprises copolymerizing a small amount of apolyolefinic monomer, preferably a polyvinyl aromatic monomer, as across-linking ingredient, with a halostyrene in which the halogen has anatomic number greater than 17 (e.g., bromo or iodostyrene) or analkylated derivative thereof. If desired, a third monoolefin which iscopolymerizable with the polyvinyl aromatic compound and the halostyrene or alkylated derivative thereof can be present. Included amongsuch monoolefinic compounds are styrene, a-methyl styrene, vinyltoluene, t-butylstyrene, the vinyl xylenes, isopropenyl toluene,isopropenyl xylenes, ethylstyrenes, and ethyl isopropenylbenzenes, wherestyrene is preferred.

The resulting copolymer is cross-linked through saturated aliphaticcarbon-to-carbon bonds and is insoluble in any known solvent, but can beswollen by the solvents mentioned above as being useful for thedehydrohalogenation. The halostyrene-containing cross-linked polymer isswollen in a solvent and converted to an aryl lithium with anorganolithium. The lithiated polymer is then reacted with adiorganochlorophosphine to form the corresponding phosphines as pendantgroups.

The phosphine is reacted with an alkyl halide to form the phosphoniumhalide and then dehydrohalogenated, as described above.

In an alternative procedure monomeric vinylphenyl dihydrocarbylphosphineis polymerized, either alone or with a co-monoolefinic monomer, asdescribed above, with the cross-linking agent. In this manner theproportion of alkylidene phosphorane pendant groups on the polymermolecule can be controlled with great accuracy.

The polymerization of the mixture of monomers can be effected by freeradical catalysts, by ionizing or ultra violet radiation or by heat.Included among the effective free radical catalysts are the organicperoxides of which benzoyl peroxide, lauroyl peroxide,t-butylperbenzoate or the various other known peroxide catalysts, andthe various known diazo compounds of which azobisisobutyronitrile is arepresentative. Mixtures of catalysts can be used, if desired.

The amount of catalyst can vary from about 0.1 to about 5 percent byweight of the mixture, the upper limit being only a practical figure.

The cross-linking agents must be polyolefinic, e.g., must contain atleast two polymerizable vinyl groups. It is preferably a polyolefinichydrocarbon. Included among these are divinylbenzene, trivinylbenzene,or diisopropenylbenzene. The cross-linking agents can be used inadmixture with each other if desired.

The proportion of cross-linking agent can range from about 0.1 to about5 percent by weight of the monomers. The amount of vinyl phenyldihydrocarbylphosphine or its precursor can range from about 10 to about99.9 percent by weight of the polymerizable mixture. Preferably thevinyl phenyl dihydrocarbylphosphine or its precursor is from about 20 toabout 50 weight percent and a monoolefinic comonomer is between aboutand 50 weight percent.

A method of synthesizing p-vinyltriphenylphospine and itshomopolymerization and copolymerization with styrene to form linearpolymers is disclosed in Die Makromolekulare Chemie, V. 62, P. 183-195.Conversion of the linear polymers to the methyl phosphonium iodide withCH is also disclosed.

The preparation of the precursor cross-linked polymer having pendantphenyl dihydrocarbylphosphine groups can be effected by polymerizationin bulk, in solution in an inert solvent, such as a hydrocarbon solventrepresented by toluene, in emulsion or in suspension. The suspensionprocedure is preferred because it produces small fairly uniform beads,which physical form is most desirable for our purposes.

The temperature of polymerization can range from about 40 to about 200C., the preferred temperature depending in each case upon the catalystemployed.

Pressure has no effect on the polymerization and so autogenous pressureis preferred.

The examples which follow are intended to illustrate, but not to limitthe invention. All parts or percentages are by weight unless otherwiseindicated.

Example I Preparation of Precursor Alkyl Phosphonium Halidep-Styryldiphenylphosphine was prepared by reacting with (Cd-1 h P C1 bythe procedure described in .1. Organic Chem. 26,4157 (1961 A mixture of4.9 weight parts of p-styryldiphenylphosphine, 5.2 weight parts ofstyrene and 0.16 ml. of divinylbenzene (95 percent purity) and 0.09weight parts of azobisisobutyronitrile was agitated until solutionresulted. The solution was suspended in 64 ml. of an aqueous phasecontaining 0.19 percent methylcellulose, 0.15 percent sodium dichromateand 0.5 percent sodium sulfate. The suspension was heated for about 3hours at about 70 C. The cross-linked copolymeric beads were washed withbenzene and dried. Elemental analysis verified that the theoreticalamount of phosphorus was present in the polymeric molecule.

The crosslinked polymeric beads. having a carbonto-carbon backbone andcontaining a total 0.67 mmoles of triphenylphosphine pendant groups weremixed with a solution of three mmoles of methyl iodide indimethylsulfoxide. This procedure resulted in substantially completeconversion of the pendant groups to the methyl triphenylphosphoniumiodide derivative in about one hour. Excess methyl iodide was removed bywashing with a mixture of dimethylsulfoxide and tetrahydrofuran.

Example 11 Preparation of Precursor Alkyl Phosphonium Halide A. Amixture containing a 3:1 molar ratio of styrene and p-bromostyrene and1.6 percent, based on the total moles of mixture, of divinyl benzene waspolymerized at about 80 C., in an aqueous medium containing 0.19 percentmethylcellulose, and 0.05 percent sodium dichromate. The cross-linkedstyrene-p-bromostyrene copolymer was in the form of fine beads.

One gram of the beads was swollen in a mixture of 7 ml. tetrahydrofuranand seven ml. benzene. Approximately four moles of n-butyllithiumdissolved in hexane were added to the copolymer-solvent mixture, and thelatter was stirred for about 4 hours. The resulting lithioderivative waswashed with several portions of diethylether, resuspended intetrahydrofuran in a nitrogen atmosphere and treated with 2.4 mmoles ofchlorodiphenylphosphine to form triphenylphosphine pendant groups on thecross-linked polymer. After about l-V4 hours excess reagent andby-produets were removed by several washings with tetrahydrofuran whileexcluding air from the system. 5.3 mmoles of methyl iodide was added toa tetrahydrofuran suspension of the phosphine-containing polymers toconvert the pendant groups to the triphenylmethylphosphonium iodidederivatives. This step was carried out in a nitrogen atmosphere. Thesuspension was stirred over night at room temperature. Excess methyliodide was removed by several washings of the phosphonium salt form ofthe polymer with tetrahydrofuran. Elemental analysis of the salts showedabout a quantitative conversion of the polymer to phosphonium salt. Thesalt is stable in air.

Preparation of the Polymeric Ylide The above-described cross-linkedpolymer having a carbon-to-carbon backbone, with a plurality of methyltriphenylphosphonium iodide pendant groups was suspended in 10 ml.tetrahydrofuran from which air was excluded by use of nitrogenatmosphere. Swelling required about 3 to 4 hours. A solution of 3.2mmoles of n-butyllithium in hexane was added to the mixture and stirredfor about three hours. The supernatant liquid was removed and the beadswere washed several times, over a 6 hour period, with tetrahydrofuran.

The polymeric beads, having methylene triphenylphosphorane pendantgroups was suspended in five ml. tetrahydrofuran in a nitrogenatmosphere and a 0.3 ml. of cyclohexanone was added. The supernatantliquid was separated by gas chromatography and showed a peak formethylene eyclohexane. it is estimated that about 20 percent of thecyclohexanone was converted to methylene cyclohexane.

Preparation of Methylene Tn'ph enyl Phosphorane This reaction wascarried out in a nitrogen atmosphere. To the methyl triphenylphosphonium iodide was added a solution of 3.2 mmoles of sodiumdimethylsulfoxide anion in a mixture of dimethylsulfoxide andtetrahydrofuran as the dehydrohalogenating agent. The mixture wasstirred for approximately 16 hours. The supernatant liquid wasseparated. The polymer containing methylene triphenylphosphorane groupswas washed several times with tetrahydrofuran. To the resin were added0.48 moles of cyclohexanone. Analysis of the supernatant liquid by gasliquid chromatography showed that about percent of the cyclohexanone wasconverted to methylenecyclohexane.

It is apparent that can be reacted with other dihydrocarbylchlorophosphines to form derivatives of the structure The lattercompounds can be polymerized with a polyolefinic cross-linking agent orwith the cross-linking agent and one or more other monoolefinic monomersas described above. The resulting crosslinked polymer can then beconverted to one having alkyl phosphonium halide groups, and, bydehydrohalogenation of the latter, to a polymer having a plurality ofalkylidene dihydrocarbyl phosphorane groups, by following the aboveprocedure.

We claim:

l. lnsoluble aromatic addition polymers, cross-linked throughcarbon-to-carbon bonds derived from copolymerizing from about 0.1 toabout 5 weight percent ofa polyolefinic monomer with from about 99.9 toabout weight percent of a monoolefinic aromatic monomer, said polymershaving from about 10 to about 99.9 weight percent of P CRJRl pendantgroups on a carbon-to-carbon polymer backbone, wherein R and R eachindependently is an alkyl group having from one to about l C atoms, acycloalkyl group, an aromatic hydrocarbon substituted cycloalkyl group,a C -C, alkyl substituted cycloalkyl group in which the substituentsrange from one to the number sufiicient to replace each hydrogen atom ofsaid cycloalkyl group, an aryl group having from one to three aromatichydrocarbon rings, a C C. alkyl substituted derivative of said arylgroups in which the number of substituents ranges from one to the numbersufficient to replace each hydrogen atom on said aryl group, the saidalkyl substituent having from one to four C atoms, when R, and R, areboth said alkyl groups (A) R and R each represents, independently, ahydrogen atom, said aryl, alkyl or cycloalkyl groups, and (B) R; and R.combined represent the moiety of fluorene and the portion of a fluorenemoiety; and when R is a hydrogen atom a said alkyl or cycloalkyl group,R represents a said aryl group, an acyl group of one to C atoms, acarbalkoxy group of from one to 10 C atoms or a cyano group.

2. The polymer of claim 1 in which R and R each is an unsubstituted arylgroup having from one to three aromatic rings.

3. The polymer of claim 2 in which R and R each is a phenyl group.

4. The polymer of claim 2 in which R and R each is a methyl substitutedphenyl group having from one to two methyl groups on the ring.

5. The polymer of claim 1 in which R and R each is an alkyl group offrom one to about four C atoms.

6. The polymer of claim I in which R, is a phenyl group and R is analkyl group of from one to about four C atoms.

7. The polymer of claim 1 in which R and R each is hydrogen.

8. The polymer of claim 1 in which R and R each is an alkyl group offrom one to about 10 C atoms.

9. The polymer of claim 1 in which R; is hydrogen and R is an alkylgroup of from one to four C atoms.

10. The polymer of claim 1 in which R;, is hydrogen and R is acarbalkoxy group of from two to 10 C atoms.

11. The polymer of claim 1 in which R is hydrogen and R is a cyanogroup.

12. A method of preparing insoluble, cross-linked addition polymers, inwhich the crosslinking occurs through carbon-to-carbon bondscopolymerization of from about 0.1 to about 5 weight percent of apolyolefinic monomer with from about 99.9 to about weight percent of amonoolefinic arm matic monomer, said polymer having from about 10 toabout 99.9 weight percent of groups on a carbon-to-carbon polymerbackbone, wherein R R R and R each have the same designations in Claim1, said method comprising swelling in a polar organic solvent, underanhydrous conditions and in an inert atmosphere an insoluble,cross-linked precursor polymer in which the pendant group has the R R Rand R are the same as above defined and X is a halogen atom, anddehydrohalogenating said precursor with an alkali metal hydrocarbylcompound.

13. The method of claim 12 in which the swelling solvent is selectedfrom the class consisting of tetrahydrofuran, liquid dialkyl ethers offrom four to 10 C atoms, cyclic ethers having four to eight C atoms,dialkoxalkanes having three to 10 C atoms, dialkyl sul foxides havingfrom two to four C atoms, hexamethylphosphoramide or dimethyl formamide,and mixtures of said solvents.

14. The method of claim 12 in which alkali metal hydrocarbyl compound isan alkyl alkali metal.

15. The method of claim 14 in which the alkyl alkali metal is an alkyllithium compound.

16. The method of claim 12 in which the pendant group of the precursorhas the structure and the dehydrohalogenating agent is sodiumdimethylsulfoxide anion in which the alkyl group has from four to five Catoms. H

17. The method of claim 15 in which the swelling agent is a mixture oftetrahydrofuran and dimethylsulfoxide.

through

2. The polymer of claim 1 in which R1 and R2 each is an unsubstitutedaryl group having from one to three aromatic rings.
 3. The polymer ofclaim 2 in which R1 and R2 each is a phenyl group.
 4. The polymer ofclaim 2 in which R1 and R2 each is a methyl substituted phenyl grouphaving from one to two methyl groups on the ring.
 5. The polymer ofclaim 1 in which R1 and R2 each is an alkyl group of from one to aboutfour C atoms.
 6. The polymer of claim 1 in which R1 is a phenyl groupand R2 is an alkyl group of from one to about four C atoms.
 7. Thepolymer of claim 1 in which R3 and R4 each is hydrogen.
 8. The polymerof claim 1 in which R3 and R4 each is an alkyl group of from one toabout 10 C atoms.
 9. The polymer of claim 1 in which R3 is hydrogen andR4 is an alkyl group of from one to four C atoms.
 10. The polymer ofclaim 1 in which R3 is hydrogen and R4 is a carbalkoxy group of from twoto 10 C atoms.
 11. The polymer of claim 1 in which R3 is hydrogen and R4is a cyano group.
 12. A method of preparing insoluble, cross-linkedaddition polymers, in which the cross-linking occurs throughcarbon-to-carbon bonds through copolymerization of from about 0.1 toabout 5 weight percent of a polyolefinic monomer with from about 99.9 toabout 95 weight percent of a monoolefinic aromatic monomer, said polymerhaving from about 10 to about 99.9 weight percent of
 13. The method ofclaim 12 in which the swelling solvent is selected from the classconsisting of tetrahydrofuran, liquid dialkyl ethers of from four to 10C atoms, cyclic ethers having four to eight C atoms, dialkoxalkaneshaving three to 10 C atoms, dialkyl sulfoxides having from two to four Catoms, hexamethylphosphoramide or dimethyl formamide, and mixtures ofsaid solvents.
 14. The method of claim 12 in which alkali metalhydrocarbyl compound is an alkyl alkali metal.
 15. The method of claim14 in which the alkyl alkali metal is an alkyl lithium compound.
 16. Themethod of claim 12 in which the pendant group of the precursor has thestructure
 17. The method of claim 15 in which the swelling agent is amixture of tetrahydrofuran and dimethylsulfoxide.